A new method for evaluating distance stereo acuity.

A new standardized method for evaluating distance stereo acuity has been developed, using the graphic capacity of a high-frequency microprocessor and liquid crystal binocular glasses. Images are alternately presented at a frequency of 60 cycles per second to each eye, using synchronized liquid crystal shutter glasses. The amount of disparity in the stereo patterns can be altered to allow a measurement as refined as 15 seconds of arc ("). This instrument is now commercially available as part of the Mentor B-Vat system. We evaluated distance Random Dot and Contour circle stereo acuity of 50 normal subjects using this new method and compared these results to conventional Titmus and Randot circles at near. The distance stereo acuity mean results were 139" for the Random Dot test and 41.1" for the Contour circles. The near stereo acuity results were 41.8" for the Titmus circles and 27" for the Randot circles. Statistically, the Titmus results at near can be compared to the Contour circles at distance. The distance Random Dot test results demonstrate much less stereoability than the other test. The application of these new distance stereotests will be discussed.